Stackable chair



FIG. 1 is a front perspective view of a stackable chair showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a side view thereof; the other side being a mirror image thereof;

FIG. 4 is a rear view thereof;

FIG. 5 is a top view at a slightly oblique angle thereof; and

FIG. 6 is a bottom view thereof. 

The ornamental design for a stackable chair, as shown and described. 